This invention relates generally to test equipment, and more particularly, to test equipment and test methods employing signature analysis to achieve fault isolation of digital modules.
There are three methods that are currently used for fault isolation in digital modules. These include manual isolation using a digital voltmeter, scope, and schematic as is done by commercial off-the-shelf suppliers. The second method is to use a fault dictionary along with expensive automatic test equipment. The third method uses guided probing that is directed by expensive automatic test equipment.
Manual isolation is time consuming and very costly in terms of labor expenses. Fault dictionary isolation is not accurate enough to isolate to a single bad node or part. Guided probing is not allowed in some applications (such as a Navy depot test, for example), and is not possible in some applications (such as temperature environments and new sealed chip on-board modules. It is also desirable to minimize the use of expensive automatic test equipment.
Accordingly, it is an objective of the present invention to provide for test equipment and test methods employing signature analysis to achieve fault isolation of digital modules.